MMVD stands for Myxomatous Mitral Valve Disease, also known as degenerative mitral valve disease.
The exact cause of MMVD is still unknown, but we do know that it commonly affects small to medium breed dogs. Certain breeds, such as Cavalier King Charles spaniels, Dachshunds, and Chihuahuas, can develop MMVD at a younger age, suggesting a genetic component.
In MMVD, the mitral valve, which acts like a door in the heart, becomes thickened and loses its function. This leads to blood leaking back from the left ventricle into the left atrium because the “door” isn’t closing tightly.
The severity of the condition depends on how much blood leaks and whether it causes the left heart chambers to enlarge. A cardiologist evaluates MMVD and categorizes it into five stages: A, B1, B2, C, and D.
When a dog’s heart chambers are enlarged (in stages B2, C, and D), treatment is indicated. The medication(s) can delay the progression of the disease but does not cure it. Some dogs have a slow progression while some dogs deteriorate rapidly. In humans, MMVD often requires surgery for a cure. However, surgery in dogs is complex and super expensive, and it’s only available in certain countries like Japan and the UK.
“MMVD in dogs requires surgery to achieve a complete cure. Medications do not cure but delay progression and improve life quality.”
In recent years, a minimally invasive trans-catheter edge-to-edge technique (using V-clamp by Hongyu Medical, China) has become available. This procedure involves a small incision on the chest and heart and clamping the parts of the mitral valve that are causing the leakage. It’s less expensive and can be performed within 2-3 hours without stopping the heart or using a cardio-pulmonary bypass machine.
However, for a few months after the surgery, the dogs typically have to take a blood thinner to prevent blood clot formation. Besides, not all dogs are suitable candidates for this procedure, and responses can vary. Factors such as body size and mitral valve or annular pathology, and other concurrent diseases may disqualify a dog from undergoing the procedure.
Post-V-clamp surgery, dogs may require fewer or lower doses of cardiac medications, reducing the burden of long-term medication management and costs. In some cases, cessation of certain cardiac medications may be possible.
At present, countries such as South Korea, the UK, and Thailand have reported a good success rate in dogs which underwent the procedure.
In May 2024, the Shinzō team underwent intensive training on V-clamp surgery in Shanghai, China. Subsequently, in December 2024, we successfully performed the procedure on a dog. We are committed to improving the quality of life and survival rates for dogs with advanced MMVD.
